Heat Exchanger

ABSTRACT

A heat exchanger with reduced pressure loss, and improved productivity and strength. The heat exchanger is made by laminating first heat conduction plates and second heat conduction plates alternately. A first heat conduction plate and a second heat conduction plate are integrally molded of one sheet. The sheet includes air duct ribs, heat conduction planes, air duct end faces, first protrusions, first outer peripheral ribs, second outer peripheral ribs, air duct end covers, and second protrusions.

TECHNICAL FIELD

The present invention relates to a heat exchanger for use in a heatexchange ventilator or air conditioner.

BACKGROUND ART

Recent years, heat exchanger type ventilating fans effective in savingenergy have been popular. A heat exchanger for exchanging heat betweenindoor and outdoor air can save energy in an air conditioning device byrecovering heat lost during ventilation of indoor air. An example of acounter flow system heat exchanger is disclosed in Unexamined JapaneseUtility Model Publication No. 1981-89585.

Hereinafter, a description is provided of the conventional heatexchanger with reference to FIGS. 30 through 32.

As shown in FIG. 30, L-shaped spacers 102, each protruding so that thebackside thereof is recessed to have a substantially V-shaped section,are formed on the surface of heat conduction plate 101 made of a plasticmaterial, such as a rigid vinyl sheet.

A plurality of spacers 102 are spaced with each other to form heatconduction plane 103. The periphery of heat conduction plate 101 formsbent edges 104 that open slightly outward of the plane perpendicular tothe plate.

At both ends of spacers 102 and along the outside halves of bent edges104 a and 104 b facing the ends, slots 105 a and 105 b are provided asair inlets and outlets, respectively. Additionally, along the insidehalves of the other bent edges 104 c and 104 d, slots 105 c and 105 dare provided as the air inlets and outlets symmetrically with slots 105a and 105 b formed along the outside halves, respectively.

Then, laminating a plurality of heat conduction plates 101 so as to bepositioned in orientations 180 degrees different from each other in oneplane provides heat exchanger 106 as shown in FIG. 31.

As shown in FIG. 32, spacers 102 on heat conduction plate 101 andspacers 102 on adjacent heat conduction plate 101 are positionedparallel but misaligned to each other so as not to overlap. In thismanner, the apexes of spacers 102 on a heat conduction plate are incontact with the top surface of heat conduction plane 103 of theadjacent heat conduction plate, and the outside half of bent edge 104overlaps the inside half of adjacent bent edge 104. Thus, two kinds ofair channels 107 a and 107 b divided into a plurality of L-shaped airducts by spacers 102 are alternately formed between these heatconduction plates 101. At one end of each channel, slots 105 a or 105 cin the bent edges form inlets. At the other end of each channel, slots105 b or 105 d in the bent edges form outlets, in the similar manner.

The arrows in FIG. 32 show fluid flows.

In the above conventional heat exchanger, no air flows through theportion of spacer 102 having substantially a V-shaped section. For thisreason, in the portion in which apex W of spacer 102 is in contact withheat conduction plane 103 of heat conduction plate 101, no heat isexchanged. Reducing the area of apex W by substantially V-shaping thesection of spacer 102 intends to reduce the area in which no heat isexchanged. However, spacers 102 on heat conduction plate 101 and spacers102 on adjacent heat conduction plate 101 are positioned parallel butmisaligned to each other not to overlap, and apexes W of spacers 102 arein contact with the top surface of heat conduction plane 103 on theadjacent heat conduction plate. This structure doubles the portion of noheat exchange on heat conduction plate 101 and heat conduction plate 101under the former plate.

As a result, this structure poses a problem that reduction in effectiveheat transfer area deteriorates heat exchange efficiency. Thus,increases in the heat transfer efficiency are required.

Additionally, in heat exchanger 106 obtained by laminating a pluralityof heat conduction plates 101 in orientations 180 degrees different fromeach other in one plane, only spacers 102 support the spacing betweenheat conduction plates 101.

For this reason, weight of the plurality of laminated heat conductionplates 101 or external force exerted thereon can deform spacers 102 andair channels 107 a and 107 b can collapse. This poses a problem ofdecreasing the opening areas of the channels and increasing pressureloss. Thus, improvement of strength and reduction in pressure loss arerequired.

Heat conduction plate 101 is obtained by vacuum-molding a plasticmaterial, such as a rigid vinyl sheet, and cutting five portions, i.e.the outer periphery of bent edges 104 and slots 105 a, 105 b, 105 c, and105 d in the bent edges. At this time, it is difficult to cut out theouter periphery of bent edges 104 in a vertical direction and four slotsin the bent edges in a horizontal direction by one step. This poses aproblem of low production efficiency, and thus improvement thereof isrequired.

In the outer peripheries near the inlets and outlets of heat exchanger106, because bent edges 104 of heat conduction plate 101 are in contactwith spacers 102 on another heat conduction plate 101 laminated thereon,spacers 102 prevent bent edges 104 from being deformed by lateralexternal force. Thus, air-tightness is unlikely to be deteriorated bydeformation of bent edges 104.

However, the outer peripheries in the portions other than the inlets oroutlets in heat exchanger 106 only has contact of bent edges 104 of heatconduction plate 101 with bent edges 104 of another heat conductionplate 101 laminated thereon. Thus, bent edges 104 are likely to bedeformed by lateral external force. This poses a problem thatdeformation of bent edges 104 deteriorates air-tightness. Thus,improvement of strength and a highly air-tight structure are required.

The present invention aims to address these conventional problems, andprovides a heat exchanger having improved basic performance, such asincreasing heat exchange efficiency and decreasing pressure loss, aswell as improved productivity and strength.

SUMMARY OF THE INVENTION

The present invention provides a heat exchanger including first heatconduction plates and second heat conduction plates, each insubstantially a square shape. Each of the first and second heatconduction plates includes: a plurality of substantially L-shaped airduct ribs forming a plurality of substantially L-shaped air ducts andheat conduction planes; outer peripheral ribs for shielding leak offluid flowing through the air ducts to the outside of the heatconduction plate; and an air-tightness ensuring means. The first heatconduction plate and the second heat conduction plate are integrallymolded of one sheet material. The first heat conduction plates and thesecond heat conduction plates are alternately laminated on top of eachother.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view in perspective of a heat exchanger inaccordance with a first exemplary embodiment of the present invention.

FIG. 2 is a perspective view of the heat exchanger in accordance withthe first exemplary embodiment in a laminated state.

FIG. 3 is a section of a side portion of the heat exchanger inaccordance with the first exemplary embodiment in the laminated state.

FIG. 4 is a section of an air duct inlet and outlet portion of the heatexchanger in accordance with the first exemplary embodiment in thelaminated state.

FIG. 5 is a section of a corner portion in which second peripheral ribs12 on first heat conduction plate 1 and second heat conduction plate 2in the laminated state intersect with each other in the heat exchangerin accordance with the first exemplary embodiment.

FIG. 6 is an enlarged view in perspective of a corner portion in whichair duct inlets and outlets are adjacent to each other in the heatexchanger in accordance with the first exemplary embodiment in thelaminated state.

FIG. 7 is an enlarged view in perspective of a portion in which air ductinlets and outlets are adjacent to first outer peripheral ribs 11 in theheat exchanger in accordance with the first exemplary embodiment in thelaminated state.

FIG. 8 is a perspective view illustrating a method of molding the heatconduction plates of the heat exchanger in accordance with the firstexemplary embodiment.

FIG. 9 is an exploded view in perspective of a heat exchanger inaccordance with a second exemplary embodiment of the present invention.

FIG. 10 is a perspective view of the heat exchanger in accordance withthe second exemplary embodiment in a laminated state.

FIG. 11 is a section of a side portion of the heat exchanger inaccordance with the second exemplary embodiment in the laminated state.

FIG. 12 is an exploded view in perspective of a heat exchanger inaccordance with a third exemplary embodiment of the present invention.

FIG. 13 is a perspective view illustrating the heat exchanger inaccordance with the third exemplary embodiment in a laminated state.

FIG. 14 is a section of a side portion of the heat exchanger inaccordance with the third exemplary embodiment in the laminated state.

FIG. 15 is an exploded view in perspective of a heat exchanger inaccordance with a fourth exemplary embodiment of the present invention.

FIG. 16 is a perspective view illustrating the heat exchanger inaccordance with the fourth exemplary embodiment in a laminated state.

FIG. 17 is an exploded view in perspective of a heat exchanger inaccordance with a fifth exemplary embodiment of the present invention.

FIG. 18 is a perspective view illustrating the heat exchanger inaccordance with the fifth exemplary embodiment in a laminated state.

FIG. 19 is a section illustrating a side portion of the heat exchangerin accordance with the fifth exemplary embodiment in the laminatedstate.

FIG. 20 is an exploded view in perspective of a heat exchanger inaccordance with a sixth exemplary embodiment of the present invention.

FIG. 21 is a perspective view illustrating the heat exchanger inaccordance with the sixth exemplary embodiment in a laminated state.

FIG. 22 is a section illustrating a side portion of the heat exchangerin accordance with the sixth exemplary embodiment in the laminatedstate.

FIG. 23 is an exploded view in perspective of the heat exchanger inaccordance with the sixth exemplary embodiment of the present invention.

FIG. 24 is a perspective view illustrating the heat exchanger inaccordance with the sixth exemplary embodiment in a laminated state.

FIG. 25 is an exploded view in perspective of a heat exchanger inaccordance with a seventh exemplary embodiment of the present invention.

FIG. 26 is a perspective view of the heat exchanger in accordance withthe seventh exemplary embodiment in a laminated state.

FIG. 27 is a section illustrating a side portion of the heat exchangerin accordance with the seventh exemplary embodiment in the laminatedstate.

FIG. 28 is an exploded view in perspective of a heat exchanger inaccordance with an eighth exemplary embodiment of the present invention.

FIG. 29 is a perspective view illustrating the heat exchanger inaccordance with the eighth exemplary embodiment in a laminated state.

FIG. 30 is a perspective view of unit components of a conventional heatexchanger.

FIG. 31 is a perspective view of the conventional heat exchanger in alaminated state.

FIG. 32 is a section of a central portion of the conventional heatexchanger in the laminated state.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention are detailedwith reference to the accompanying drawings. The drawings are schematicand do not show the correct dimensions of the positions. In therespective exemplary embodiments, same elements are denoted with thesame reference marks, and the detailed descriptions thereof are omitted.

In each of the exemplary embodiments, only four heat conduction platesare shown for simplicity. However, actually, a plurality of first andsecond heat conduction plates are laminated alternately.

FIRST EXEMPLARY EMBODIMENT

With reference to FIGS. 1 to 3, the first exemplary embodiment isdescribed.

As shown in FIGS. 1 and 2, a counter-flow type heat exchanger is made bylaminating first heat conduction plates 1 and second heat conductionplates 2 alternately.

Then, first air ducts 3 and second air ducts 4 are formed over and underthe respective heat conduction plates. Fluids flowing through firstducts 3 exchange heat via the respective heat conduction plates. Thefluids flow in the orthogonal direction with each other at therespective inlets and outlets of the air ducts, and in the facingdirection with each other in the central portions of the air ducts.

Each of first heat conduction plates 1 and second heat conduction plates2 is made by vacuum-molding a polystyrene sheet having a square planeshape and a thickness of 0.2 mm, for example. First heat conductionplate 1 includes three substantially L-shaped air duct ribs 6 at anequal spacing in parallel with each other. Each of the ribs is a hollowprotrusion 2 mm high and 2 mm wide, for example, formed on heatconduction plane 5.

Air duct ribs 6 form substantially L-shaped first air ducts 3 and heatconduction planes 5. Along each of the inlet and outlet of first airducts 3, air duct end face 7 is provided. The air duct end face is madeby bending the edge of first heat conduction plate 1 in a directionopposite to the protruding direction of air ducts 6 to a position 2.2mm, for example, from heat conduction plane 5. Then, at each of bothends of air duct ribs 6, a plurality of first protrusions 8 are providedin six positions, for example. Each of the first protrusions is hollowin the protruding direction of air duct ribs 6 and higher than the airduct ribs, e.g. 4 mm high from heat conduction plane 5.

Each of first protrusions 8 includes side surface 9 parallel to air ductend face 7, and top surface 10 parallel to heat conduction plane 5.Along the outer peripheries of first heat conduction plate 1 other thanthe inlets and outlets of first air ducts 3 and substantially parallelto the air duct portions sandwiched between the inlets and outletsthereof to provide counter flows, first outer peripheral rib 11 a isprovided. The first outer peripheral rib is a hollow protrusion in theprotruding direction of air duct ribs 6 having a height equal to that offirst protrusions 8, and a width of 4 mm, for example. Provideddiagonally of first peripheral rib 11 a is first outer peripheral rib 11b shaped identical thereto. The top surface of each of first outerperipheral ribs 11 is parallel to heat conduction plane 5, and the outerside surface thereof is bent to the same position as air duct end face7. Provided along the outer peripheries of first heat conduction plate 1other than the inlets and outlets of first air ducts 3 and first outerperipheral ribs 11 are second outer peripheral ribs 12(a and b) shapedidentical to each other.

Now expression 12(a and b) in the present invention is described.Expression 12 indicates both 12 a and 12 b. Among the other cases,expression 11(c and d), for example, indicates both 11 c and 11 d.Second outer peripheral rib 12 a is substantially parallel to firstouter peripheral ribs 11. Second outer peripheral rib 12 b issubstantially orthogonal to first outer peripheral ribs 11. Each of thesecond outer peripheral ribs is a hollow protrusion in the protrudingdirection of air duct ribs 6 having a height equal to that of air ductribs 6, and width of 7 mm, for example.

The top surface of each of second outer peripheral ribs 12 is parallelto heat conduction plane 5. The central portion of the outer sidesurface of each second outer peripheral rib is bent to the position ofheat conduction plane 5 to form air duct slot 13. Further, each of theends of each second outer peripheral rib is bent to the position of airduct end face 7 in a portion of 5 mm, for example, from the corner, toform air duct end face cover 14.

On the side of air duct end face 7, each of second outer peripheral ribs12 has second protrusion 15 a formed as a hollow protrusion in theprotruding direction of air duct ribs 6 having a height equal to that offirst protrusion 8 and a width of 3 mm, for example.

Second protrusions 15 a are substantially orthogonal to secondprotrusions 15 b provided on second heat conduction plate 2 positionedthereon.

The top surfaces of second protrusions 15 a are in contact with thebottom surfaces of second outer peripheral ribs 12 on second heatconduction plate 2 positioned thereon.

Second heat conduction plate 2 is analogous to first heat conductionplate 1. In second heat transfer plate 2, each of first outer peripheralribs 11(c and d) is as high as air duct ribs 6. Further, each of firstouter peripheral ribs 11(c and d) on second heat conduction plate 2 iswider (e.g. 7 mm) than each of outer peripheral ribs 11(a and b) onfirst heat conduction plate 1.

The heat exchanger is formed as shown in FIG. 3 when first heatconduction plates 1 and second heat conduction plates 2 are alternatelylaminated. The top surfaces of first outer peripheral ribs 11(a and b)on the first heat conduction plates are in close contact with firstouter peripheral ribs 11(c and d) on second heat conduction plates 2,respectively, laminated thereon. Further, the top surfaces of firstouter peripheral ribs 11(c and d) on second heat conduction plates 2 arein close contact with first outer peripheral ribs 11(a and b) on firstheat conduction plates 11, respectively, laminated thereon. The outersurfaces of the outer sides of first outer peripheral ribs 11 are inclose contact with the inner surfaces of the inner sides of outerperipheral ribs 11 on the adjacent plates. In this manner, air ducts 3and second air ducts 4 are tightly sealed along each of first outerperipheral ribs 11.

Along the outer peripheries of the heat exchanger, the spacing betweenair duct ribs 6 on a heat conduction plate and another heat conductionplate laminated thereon is kept by contact of the top surfaces of firstouter peripheral ribs 11 on the heat conduction plate with the bottomsurfaces of first outer peripheral ribs 11 on the other heat conductionplate laminated thereon, contact of the top surfaces of firstprotrusions 8 at the inlets and outlets of first air ducts 3 and secondair ducts 4 with the bottom surfaces of second outer peripheral ribs 12on the other heat conduction plate laminated thereon, and contact of thetop surfaces of second protrusions 15 at end faces of second outerperipheral ribs 12 with the bottom surfaces of second outer peripheralribs 12 on the other heat conduction plate laminated thereon.

Further, in a portion near the inlets and outlets of the heat exchangerwhere airflows are orthogonal to each other, the spacing is kept bycontact of air duct ribs 6 with heat conduction planes 5 of the otherheat conduction plate laminated thereon. Such contact can securely keepthe height of first air ducts 3 and second air ducts 4.

This air duct height is designed according to performance, such asairflow resistance, and moldability of the heat exchanger.

In substantially central portions of the side surfaces of the heatexchanger, air duct ribs 6 on first heat conduction plates 1 and secondheat conduction plates 2 are placed in vertically aligned positions.

When the airflows through first air ducts 3 and second air ducts 4 inthe opposed direction exchange heat via heat conduction planes 5, no airflows through air duct ribs 6 formed by the heat transfer plates intosubstantially L-shaped hollow protrusions, and thus no heat is exchangedtherein. Placing air duct ribs 6 on first heat conduction plates 1 andsecond heat conduction plates 2 in vertically aligned positions canminimize the area of no heat exchange within a certain volume.

As shown in FIG. 4, at the air duct inlets and outlets, the top surfacesof second outer peripheral ribs 12 are in close contact with the heatconduction plates laminated thereon. Then, side surfaces 9 of firstprotrusions 8 parallel to air duct end faces 7 are in close contact withthe inner surfaces of the outer sides of second outer peripheral ribs 12on the transfer plates laminated thereon.

Further, top surfaces 10 of first protrusions 8 are in close contactwith the bottom surfaces of second outer peripheral ribs 12 on the heattransfer plates laminated thereon. The outer side surfaces of secondouter peripheral ribs 12 are in close contact with the inner surfaces ofair duct end faces 7 of the heat transfer plates laminated thereon. Thecomponents of the heat exchanger are formed in the above structure.

Such contact tightly seals first air ducts 3 and second air ducts 4 atthe inlets and outlets thereof, prevents misalignment of laminated heattransfer plates, and positions the heat transfer plates duringlamination.

As shown in FIG. 5, at the corners where second outer peripheral ribs12(a and b) on first heat conduction plates 1 intersect second outerperipheral ribs 12(c and d) on second heat conduction plates 2, the topsurfaces of second protrusions 15 a on the top surfaces of second outerperipheral ribs 12(a and b) are in contact with the bottom surfaces ofsecond outer peripheral ribs 12(c and d) on second heat conductionplates 2 laminated thereon. Such contact inhibits deformation of theheat conduction plates in the laminated direction and preventsair-tightness from being deteriorated by the deformation.

As shown in FIG. 6 and 7, at both ends of the inlets and outlets offirst air ducts 3 and second air ducts 4, at the corners where secondouter peripheral ribs 12(a and b) on first heat conduction plates 1intersect second outer peripheral ribs 12(c and d) on second heatconduction plates 2, the end faces of second protrusions 15 on secondouter peripheral ribs 12 are in close contact with the inner surfaces ofduct end face covers 14 on the heat conduction plates laminated thereon.In the portions where the inlets and outlets of first air ducts 3 orsecond air ducts 4 are adjacent to first outer peripheral ribs 11, theend faces of first outer peripheral ribs 11 are in close contact withthe inner surfaces of air duct end face covers 14 on the heat conductionplates laminated thereon.

Such contact ensures the air-tightness at both ends of side surfaces offirst air ducts 3 and second air ducts 4.

As shown in FIG. 8, first heat conduction plate 1 and second heatconduction plate 2 are integrally molded, using a molding die that hassquare parts continuing to the outer side surfaces of second outerperipheral ribs 12 and having a sectional shape identical to that of theslots formed in the outer side surfaces of second outer peripheral ribs12.

After molding, the part other than slot-forming portions 16 made of thesquare parts is cut out at a time using a Thompson type die or the like,along the outer side surfaces of first heat conduction plate 1 andsecond heat conduction plate 2. Thus, molded sheets of first heatconduction plate 1 and second heat conduction plate 2 are obtained.

The above structure can enhance the air-tightness of the inlets andoutlets of first air ducts 3 and second air ducts 4 and along sidesurfaces of a heat exchanger, and thus the air-tightness of the entireheat exchanger.

Air duct ribs 6 substantially parallel to first outer peripheral ribs 11on first heat conduction plates 1 and second heat conduction plates 2are in vertically aligned positions. As a result, when heat is exchangedby airflows through first air ducts 3 and second air ducts 4 formed byalternately laminating first heat conduction plates 1 and second heatconduction plates 2, no heat is exchanged in air duct ribs 6 formed intosubstantially L-shaped hollow protrusions by the heat conduction plates.In this manner, placing air duct ribs 6 on first heat conduction plates1 and second heat conduction plates 2 in vertically aligned positionscan minimize the area of no heat exchange within a certain volume.

In other words, this structure can provide a larger effective heattransfer area and heat exchange effectiveness than a structure havingvertically misaligned air duct ribs 6 on heat conduction plates.

Along the outer peripheries of the inlets and outlets of first air ducts3 and second air ducts 4 of the heat exchanger, contact of second outerperipheral ribs 12 on the heat conduction plates with air duct end faces7 on the heat conduction plates laminated thereon prevents the sidesurfaces from being deformed by external force lateral to the laminationdirection.

This prevention is provided by the cross-linking effect of firstprotrusions 8 in communication with air duct end faces 7, and theplurality of substantially L-shaped air duct ribs 6.

Further, along the outer peripheries other than the inlets and outletsof first air ducts 3 and second air ducts 4, contact of the top and sidesurfaces of first outer peripheral ribs 11 formed into hollowprotrusions by heat conduction planes 5 with the bottom and sidesurfaces of first outer peripheral ribs 11 on the heat transfer plateslaminated thereon can improve the strength against lateral externalforce. This effect is larger than the effect of the side surfaces of aheat exchanger made by simply folding the outer peripheries of the heatconduction plates thereof.

The top surfaces of first outer peripheral ribs 11 on the heatconduction plates are in contact with the bottom surfaces of first outerperipheral ribs 11 on the heat conduction plates laminated thereon. Thetop surfaces of first protrusions 8 at the inlets and outlets of firstair ducts 3 and second air ducts 4 are in contact with the bottomsurfaces of second outer peripheral ribs 12 on the heat conductionplates laminated thereon. The top surfaces of second protrusions 15 atthe end faces of second outer peripheral ribs 12 are in contact with thebottom surfaces of second outer peripheral ribs 12 on the heatconduction plates laminated thereon. Such contact can support the weightof the plurality of laminated plates and external force exerted from thetop surface in the outer peripheries of the heat exchanger. In thismanner, such contact can improve strength against external force in thelamination direction of the heat exchanger, and securely keep the heightof one heat conduction plane 5 so that air duct ribs 6 do not collapse.

As a result, this structure can secure the opening area of first airducts 3 and second air ducts 4, and thus reduce pressure loss.

First heat conduction plate 1 and second heat conduction plate 2 areformed, using a molding die that has square parts continuing to theouter side surfaces of second outer peripheral ribs 12 and having asectional shape identical to that of the slots formed in the outer sidesurfaces of the second outer peripheral ribs. First heat conductionplate 1 and second heat conduction plate 2 can be cut at a time using aThompson type die or the like, and thus the productivity can beimproved.

In this exemplary embodiment, a polystyrene sheet is used as a materialof the heat conduction plates, and the heat conduction plates areintegrally formed by vacuum molding. The materials include film made ofother thermoplastic resins, e.g. polypropylene and polyethylene, thinplate made of metal, e.g. aluminum, heat-conductive andmoisture-permeable paper materials, micro-porous resin film, and papermaterials containing resin mixed therein. The other methods ofintegrally forming the heat conduction plates using other techniques,such as air-pressure molding, very high pressure molding, and pressmolding, can also provide the similar advantages.

Resin containing rubber particles dispersed therein can also be used asa sheet material for the heat conduction plates. Specifically,styrene-based resin containing rubber particles dispersed therein, highimpact polystyrene containing rubber particles dispersed therein, andacrylonitrile-butadiene-styrene (ABS) resin containing rubber particlesdispersed therein can be used.

The styrene-based resin includes polystyrene.

In this exemplary embodiment, first heat conduction plates 1 and secondheat conduction plates 2 are integrally formed by vacuum molding method.In the vacuum molding method, after a thermo-plastic resin sheet isheated and softened, the sheet is placed on a molding die havingprotrusions and depressions and stuck to the surface of the die using avacuum pump.

Further, by dispersing rubber particles in the resin of the sheetmaterial, the elasticity of the rubber can prevent cracks of first heatconduction plate 1 and second heat conduction plate 2 during vacuummolding. The use of such material can improve the impact resistance of aheat exchanger obtained by alternately laminating first heat conductionplates 1 and second heat conduction plates 2, and thus improve thestrength thereof against cracks or impacts. Additionally, the use ofsuch material can prevent deterioration of air-tightness caused bycracks of first heat conduction plates 1 and second heat conductionplates 2, and thus improve air-tightness.

In this exemplary embodiment, the thickness of the sheet is 0.2 mm, andthe preferable thickness ranges from 0.05 to 0.5 mm (inclusive). This isbecause, at a thickness up to 0.05 mm, damage, such as breakage, islikely to occur while protrusions and depressions are molded and theheat conduction plates are handled after the molding. Further, themolded heat conduction plate is not strong and is difficult to handlewith. In contrast, at a thickness exceeding 0.5 mm, the heatconductivity deteriorates.

Generally, sheets having the smaller thickness tend to have the higherheat conductivity and lower moldability. In contrast, those having thelarger thickness tend to have the lower heat conductivity.

For the above reasons, preferably, the thickness of the sheet materialranges from 0.05 to 0.5 mm to provide satisfactory moldability and heatconductivity. Most preferably, the thickness thereof ranges from 0.15 to0.25 mm (inclusive).

The dimension and the number of components shown in this embodiment areonly an example. The present invention is not limited to these values.Heat exchangers appropriately designed according to performance, e.g.air flow resistance and heat exchange efficiency, and moldabilitythereof, can provide the similar advantages.

SECOND EXEMPLARY EMBODIMENT

A description is provided of the second exemplary embodiment, withreference to FIGS. 9 through 11.

As shown in FIGS. 9 and 10, a plurality of third protrusions 17 formedinto hollow protrusions in the protruding direction of air duct ribs 6at a height equal to that of first protrusions 8 are provided on airduct ribs 6 substantially parallel to first outer peripheral ribs 11 onfirst heat conduction plates 1 and second heat conduction plates 2.

As shown in FIG. 11, the top surfaces of third protrusions 17 are incontact with the bottom surfaces of air duct ribs 6 on the heatconduction plates positioned thereon.

In the above structure, air duct ribs 6 on first heat conduction plates1 and second heat conduction plates 2 are in vertically alignedpositions. This structure can minimize the area of no heat exchangewithin a certain volume.

As a result, this structure provides a larger effective heat transferarea and heat exchange efficiency than a structure having air duct ribs6 in vertically misaligned positions. Further, contact of the topsurfaces of the plurality of third protrusions 17 on air duct ribs 6 insubstantially the central portion of the heat exchanger with the bottomsurfaces of air duct ribs 6 formed on the heat conduction platespositioned thereon can improve the strength against the weight of theplurality of laminated heat transfer plates and external force exertedfrom the top surface. As a result, the height of one heat conductionplane 5 is securely kept so that air duct ribs 6 do not collapse. Thisstructure can secure the opening area of first air ducts 3 and secondair ducts 4, and thus improve the heat exchange efficiency and reducepressure loss.

THIRD EXEMPLARY EMBODIMENT

A description is provided of the third exemplary embodiment, withreference to FIGS. 12 through 14.

As shown in FIGS. 12 and 13, air duct rib laminations 18 formed byintermittently enlarging the width of air duct ribs 6 are provided onair duct ribs 6 substantially parallel to first outer peripheral ribs 11on first heat conduction plates 1 and second heat conduction plates 2.

For example, while each of air duct ribs 6 is 2 mm wide, each of airduct rib laminations 18 is shaped 4 mm wide. As shown in FIG. 14, airduct rib laminations 18 on first heat conduction plates 1 and secondheat conduction plates 2 are in misaligned positions in the laminationdirection.

In the above structure, the width of each air duct rib 6 isintermittently enlarged in substantially the central portion of the heatexchanger, and thus the top surfaces of enlarged air duct riblaminations 18 are in contact with heat exchange surfaces 5 around airduct ribs 6 on the heat conduction plates positioned thereon. Thiscontact can improve the strength of the heat exchanger against theweight of the plurality of laminated plates and external force exertedfrom the top surface thereof.

Such contact securely keeps the height of the one heat conduction planeso that air duct ribs 6 do not collapse, and secures the opening area offirst air ducts 3 and second air ducts 4. As a result, the area of noheat exchange can be minimized within a certain volume to improve heatexchange efficiency and reduce pressure loss.

FOURTH EXEMPLARY EMBODIMENT

A description is provided of the fourth exemplary embodiment, withreference to FIGS. 15 and 16.

As shown in FIGS. 15 and 16, a plurality of third protrusions 17 areprovided on air duct ribs 6 substantially parallel to first outerperipheral ribs 11 on first heat conduction plates 1, and air duct riblaminations 18 formed by intermittently enlarging the width of the airduct ribs on second heat conduction plates 2. The top surfaces of thirdprotrusions 17 are in contact with the bottom surfaces of air duct ribs6 on second heat conduction plates 2 positioned thereon. The topsurfaces of air duct rib laminations 18 are in contact with heatconduction planes 5 around air duct ribs 6 on first heat conductionplates 1 positioned thereon.

In this structure, the top surfaces of the plurality of thirdprotrusions 17 formed on air duct ribs 6 on first heat conduction plates1 in substantially a central portion of the heat exchanger are incontact with the bottom surfaces of air duct ribs 6 formed on secondheat conduction plates 2 positioned thereon. Further, the top surfacesof air duct rib laminations 18 formed by intermittently enlarging thewidth of air duct ribs 6 on second heat conduction plates 2 are incontact with heat conduction planes 5 around air duct ribs 6 on firstheat conduction plate s 1 positioned thereon.

This contact can improve the strength against the weight of theplurality of laminated plates and external force exerted from the topsurface, and allows the height of the one heat conduction plane 5 to bekept so that air duct ribs 6 do not collapse.

As a result, the opening area of first air ducts 3 and second air ducts4 is secured. This can minimize the area of no heat exchange within acertain volume to improve heat exchange efficiency and reduce pressureloss.

FIFTH EXEMPLARY EMBODIMENT

A description is provided of the fifth exemplary embodiment, withreference to FIGS. 17 through 19.

As shown in FIGS. 17 and 18, in substantially the central portions ofair duct ribs 6 b on second heat conduction plates 2 substantiallyparallel to first outer peripheral ribs 11, air duct rib projections 19are formed by increasing the height thereof to be equal to the height offirst protrusions 8 in the protruding direction thereof. Further, airduct ribs 6 a on first heat conduction plates 1 are made slightly largerin width than air duct ribs 6 b on second heat conduction plates 2. Forexample, while each of air duct ribs 6 b on second heat conductionplates 2 is 2 mm wide, each of air duct ribs 6 b on first heatconduction plates 1 is 4 mm wide. As shown in FIG. 19, the top surfacesof air duct ribs 6 b on second heat conduction plates 2 are in contactwith the bottom surfaces of air duct ribs 6 a on first heat conductionplates 1. Then, the top surfaces of slightly wider air duct ribs 6 a onfirst heat conduction plates 1 are in contact with heat conductionplanes 5 around air duct rib projections 19 on second heat conductionplates 2 positioned thereon.

In the above structure, the top surfaces of air duct rib projections 19on second heat conduction plates 2 having a height equal to that offirst protrusions 8 in the protruding direction thereof in substantiallythe central portion of a heat exchanger are in contact with the bottomsurfaces of wider air duct ribs 6 a on first heat conduction plates 1positioned thereon. Further, heat conduction planes 5 around air ductrib projections 19 on second heat conduction plates are in contact withthe top surfaces of air duct ribs 6 a on first heat conduction plates 1positioned thereunder. Such contact can improve the strength against theweight of the plurality of laminated heat conduction plates and externalforce exerted from the top surface, and allows the height of one heatconduction plane 5 to securely be kept so that air duct ribs 6 do notcollapse. As a result, the opening area of first air ducts 3 and secondair ducts 4 is secured. This can minimize the area of no heat exchangewithin a certain volume to improve heat exchange efficiency and reducepressure loss.

SIXTH EXEMPLARY EMBODIMENT

A description is provided of the sixth exemplary embodiment, withreference to FIGS. 20 through 22.

As shown in FIGS. 20 and 21, side face reinforcing projections 20 areprovided on the top surfaces of first outer peripheral ribs 11(c and d)on second heat conduction plates 2.

The width of each side face reinforcing projection 20 is 4 mm, forexample, equal to the width of first outer peripheral ribs 11(a and b)on first heat conduction plates 1. Each projection 20 has a continuousheight of 4 mm from the surfaces of first outer peripheral ribs 11(c andd).

As shown in FIG. 22, when first heat conduction plates 1 and second heatconduction plates 2 are alternately laminated, the top surfaces of firstouter peripheral ribs 11(a and b) on first heat conduction plates 1 arein contact with the bottom surfaces of first outer peripheral ribs 11(cand d) on second heat conduction plates 2. The top surfaces of firstouter peripheral ribs 11(c and d) on second heat conduction plates 2 arein contact with the bottom surfaces of heat conduction planes 5 on firstheat conduction plates 1. Further, the top and side surfaces of sideface reinforcing projections 20 formed on first outer peripheral ribs11(c and d) on second heat conduction plates 2 are in contact with thebottom and side surfaces of first outer peripheral ribs 11(a and b) onfirst heat conduction plates 1, respectively.

In the above structure, when the adjacent outer side surfaces of firstouter peripheral ribs 11 of a heat exchanger are heat-sealed, the hollowprotrusions of first outer peripheral ribs 11(a and b) on first heatconduction plates 1 are in contact with side face reinforcingprojections 20 on second heat conduction plates 2. When the heated heatconduction plates are melted and heat-sealed in this manner aftertemperature decrease, this structure prevents the side surfaces frombeing deformed by shrinkage resulting from temperature decrease.Further, this structure can prevent deterioration of air-tightnesscaused by deformation, and improve air-tightness of the side surfaces.

In the description of this exemplary embodiment, side face reinforcingprojections 20 have a continuous shape. However, as will be shown inFIGS. 23 and 24, a structure having intermittent side face reinforcingprojections 20 can provide the similar advantages.

SEVENTH EXEMPLARY EMBODIMENT

A description is provided of the seventh exemplary embodiment, withreference to FIGS. 25 through 27. As shown in FIGS. 25 and 26, firstouter peripheral ribs 11(a, b, c, and d) on first heat conduction plates1 and second heat conduction plates 2 are 4 mm wide, for example. Theprojections of them are 2 mm high from heat conduction planes 5.Reference marks 11(a, b, c, and d) indicate four outer peripheries 11 a,11 b, 11 c, and 11 d.

As shown in FIG. 27, first heat conduction plates 1 and second heatconduction plates 2 have intermittent side face reinforcing projections20 on the top surfaces of first outer peripheral ribs 11. The width ofeach side face reinforcing projection 20 is 4 mm, equal to the width offirst outer peripheral ribs 11(a, b, c and d), for example. The heightof the projections is 2 mm from the surfaces of first outer peripheralribs 11(a, b, c and d).

Side face reinforcing projections 20 on first heat conduction plates 1and side face reinforcing projections 20 on second heat conductionplates 2 are formed in vertically misaligned positions in the laminationdirection as follows. When first heat conduction plates 1 and secondheat conduction plate s 2 are alternately laminated, the top and sidesurfaces of side face reinforcing projections 20 on first heatconduction plates 1 are in contact with the bottom and side surfaces offirst outer peripheral ribs 11(c and d) on second heat conduction plates2, respectively. The top and side surfaces of side face reinforcingprojections 20 on second heat conduction plates 2 are in contact withthe bottom and side surfaces of first outer peripheral ribs 11(a and b)on first heat conduction plates 1, respectively.

In the above structure, when the adjacent outer side surfaces of firstouter peripheral ribs 11 of a heat exchanger are heat-sealed, the hollowprotrusions of first outer peripheral ribs 11 on first heat conductionplates 1 are in contact with the side face reinforcing projections 20 onsecond heat conduction plates 2, and the hollow protrusions of firstouter peripheral ribs 11 on second heat conduction plates 2 are incontact with side face reinforcing projections 20 on first heatconduction plates 1. Then, when the heated heat conduction plates aremelted and heat-sealed after temperature decrease, this structureprevents the side surfaces from being deformed by shrinkage resultingfrom the temperature decrease. Further, this structure can preventdeterioration of air-tightness caused by deformation, and improveair-tightness of the side surfaces.

EIGHTH EXEMPLARY EMBODIMENT

A description is provided of the eighth exemplary embodiment, withreference to FIGS. 28 through 29.

As shown in FIGS. 28 and 29, first outer peripheral ribs 11(a, b, c, andd) on first heat conduction plates 1 and second heat conduction plates 2are 4 mm wide, for example. The projections of the first heat conductionplates 1 are 4 mm high from the surface of heat conduction planes 5.Those of the second heat conduction plates are 2 mm high from thesurface of heat conduction planes 5.

Further, second heat conduction plates 2 have intermittent side facereinforcing projections 20 on the top surfaces of first outer peripheralribs 11(c and d). The width of each side face reinforcing projection 20is 4 mm, for example, equal to the width of first outer peripheral ribs11(c and d). The height the projections is 4 mm from the surfaces offirst outer peripheral ribs 11(c and d).

When first heat conduction plates 1 and second heat conduction plates 2are alternately laminated, the top and side surfaces of first outerperipheral ribs 11(a and b) on first heat conduction plates 1 are incontact with the bottom and side surfaces of first outer peripheral ribs11(c and d) on second heat conduction plates 2, respectively. The topand side surfaces of side face reinforcing projections 20 on first outerperipheral ribs 11(c and d) formed on second heat conduction plates 2are in contact with the bottom and side surfaces of first outerperipheral ribs 11(a and b) formed on first heat conduction plates 1,respectively.

In the above structure, when the adjacent outer side surfaces of firstouter peripheral ribs 11 of a heat exchanger are heat-sealed, the hollowprotrusions of first outer peripheral ribs 11(a and b) on first heatconduction plates 1 are in contact with the side face reinforcingprojections 20 on second heat conduction plates 2. Then, when the heatedheat conduction plates are melted and heat-sealed after temperaturedecrease, this structure prevents the side surfaces from being deformedby shrinkage resulting from temperature decrease. Further, thisstructure can prevent deterioration of air-tightness caused bydeformation, and improve air-tightness of the side surfaces.

As obvious form these exemplary embodiments, in the present invention,contact of the top surfaces of the first outer peripheral ribs andsecond outer peripheral ribs with the heat conduction plates positionedthereon can tightly seal the first and second air ducts, and improve theair-tightness of the entire heat exchanger. In this structure, thecross-linking effect of the first protrusions in communication with theair duct end faces and a plurality of substantially L-shaped air ductribs prevent deformation of the lateral side surfaces. Further, contactof the first outer peripheral ribs formed into hollow protrusions by theheat conduction planes with each other provides strength against lateralexternal force higher than that of the side surfaces of a heat exchangermade by simply folding the outer peripheries of the heat conductionplate. Contact of the first outer peripheral ribs, second outerperipheral ribs, first protrusions, second protrusions, air duct ribsand heat exchange surfaces on the heat conduction plates can securelykeep the height of one heat exchange surface so that the air ducts ribsdo not collapse. As a result, this structure can secure the opening areaof the first and second air ducts to reduce pressure loss.

The first heat conduction plate and second heat conduction plate areintegrally molded, using a molding die that has square parts continuingto the outer side surfaces of the second outer peripheral ribs thereofand having a sectional shape identical to that of the slots formed inthe outer side surfaces of the second outer peripheral ribs. Because thefirst heat conduction plate and second heat conduction plate can be cutat a time using a Thompson type die or the like, a heat exchanger withimproved productivity can be provided.

When heat is exchanged by airflows through the first air ducts andsecond air ducts formed by alternately laminating the first heatconduction plates and second heat conduction plates, no heat isexchanged in the air duct ribs formed into substantially L-shaped hollowprotrusions by the heat conduction plates.

Placing the air duct ribs on the first heat conduction plates and secondheat conduction plates in substantially vertically aligned positions canminimize the area of no heat exchange within a certain volume. As aresult, this structure can provide a heat exchanger having effectiveheat transfer area and heat exchange effectiveness larger than those ofa structure having heat conduction plates with the air duct ribs invertically misaligned positions.

Alternatively, contact of the top surfaces of a plurality of thirdprotrusions on air duct ribs in substantially the central portion of aheat exchanger with the bottom surfaces of the air duct ribs on the heatconduction plates positioned thereon can improve the strength thereofagainst the weight of the plurality of laminated heat conduction platesand external force exerted from the top surface.

In this manner, this structure can securely keep the height of one heatconduction plane so that the air duct ribs do not collapse, and theopening area of the first and second air ducts. Thus, this structure canprovide a heat exchanger having a minimized area of no heat exchangewithin a certain volume, to improve heat exchange efficiency and reducepressure loss.

Alternatively, the width of the air duct ribs in substantially thecentral portion of a heat exchanger is intermittently enlarged, and thusthe top surfaces of the enlarged air duct ribs are in contact with theheat conduction planes around the air duct ribs on the heat conductionplates positioned thereon.

This structure can improve the strength against the weight of theplurality of laminated plates and external force exerted from the topsurface, and can securely keep the height of one heat conduction planeso that the air duct ribs do not collapse.

Securing the opening area of the first air ducts and second air ductscan provide a heat exchanger having a minimized area of no heat exchangewithin a certain volume to improve heat exchange efficiency and reducepressure loss.

Alternatively, the top surfaces of the plurality of third protrusionsformed on the air duct ribs on the first heat conduction plates or thesecond heat conduction plates in substantially the central portionthereof are in contact with the bottom surfaces of the air duct ribsformed on the other heat conduction plates positioned thereon. Further,the width of the air duct ribs on the other heat conduction plates isintermittently enlarged. Contact of the top surfaces of the wider airduct ribs with the heat conduction planes around the air duct ribsformed on the heat conduction plates positioned thereon can improve thestrength against the weight of the plurality of laminated heat transferplates and external force exerted from the top surface.

This structure can securely keep the height of the one heat conductionplane so that the air duct ribs do not collapse, and the opening area ofthe first air ducts and second air ducts. As a result, this structurecan provide a heat exchanger having a minimized area of no heat exchangewithin a certain volume to improve heat exchange efficiency and reducepressure loss.

Alternatively, the top surfaces of the air duct ribs each having aheight equal to that of the first protrusions in substantially thecentral portion of a heat exchanger are in contact with the bottomsurfaces of wider air duct ribs on the heat conduction plates positionedthereon.

Further, the heat conduction planes around air duct ribs each having aheight equal to that of the first protrusions in the protrudingdirection are in contact with the top surfaces of the wider air ductribs on the heat conduction plates positioned thereunder. Such contactcan improve the strength against the weight of the plurality oflaminated heat conduction plates and external force exerted from the topsurface, and can securely keep the height of one heat conduction planeso that the air duct ribs do not collapse.

Securing the opening area of the first air ducts and second air ductscan provide a heat exchanger having a minimized area of no heat exchangewithin a certain volume to improve heat exchange efficiency and reducepressure loss.

Further, the top surfaces of second protrusions provided on the secondouter peripheral ribs are in contact with the bottom surfaces of thesecond outer peripheral ribs on the heat conduction plates positionedthereon.

Such contact can improve the strength of the corner portions of the heatexchanger against the weight of the plurality of laminated heatconduction plates and external force exerted from the top surface.

Further, contact of the end faces of the second protrusions provided onthe second outer peripheral ribs with the air duct end face coversformed on the heat conduction plates positioned thereon can provide aheat exchanger having improved air-tightness at the corners thereof.

Alternatively, when the adjacent outer side surfaces of the first outerperipheral ribs of a heat exchanger are heat-sealed, hollow protrusionsof the first outer peripheral ribs on the first heat conduction platesare in contact with side face reinforcing projections on second heatconduction plates. In this manner, when the heated heat conductionplates are melted and heat-sealed after temperature decrease, thisstructure prevents the side surfaces from being deformed by shrinkageresulting from temperature decrease.

As a result, this structure can provide a heat exchanger in whichdeterioration of air-tightness caused by deformation can be preventedand air-tightness of the side surfaces can be improved.

Alternatively, when the adjacent outer side surfaces of the first outerperipheral ribs of a heat exchanger are heat-sealed, the hollowprotrusions of the first outer peripheral ribs on the first heatconduction plates are in contact with the side face reinforcingprojections on the second heat conduction plates, and the hollowprotrusions of the first outer peripheral ribs on the second heatconduction plates are in contact with the side face reinforcingprojections on the first heat conduction plates.

In this manner, when the heated heat conduction plates are melted andheat-sealed after temperature decrease, this structure prevents the sidesurfaces from being deformed by shrinkage resulting from temperaturedecrease. Further, this structure prevents deterioration ofair-tightness caused by deformation.

As a result, a heat exchanger with improved air-tightness can beprovided.

Alternatively, by dispersing rubber particles in resin of the sheetmaterial, the elasticity of the rubber can prevent cracks of the firstheat conduction plates and second heat conduction plates during vacuummolding. Further, this material can improve the impact resistance of aheat exchanger obtained by alternately laminating the first heatconduction plates and second heat conduction plates, and thus improvethe strength thereof against cracks and impacts.

As a result, this material can provide a heat exchanger in whichdeterioration of air-tightness caused by cracks of the first heatconduction plates and second heat conduction plates can be prevented andthus air-tightness can be improved.

The substantially square shape in the present invention indicates ashape in which four openings in total, i.e. the inlets and outlets ofthe first and second air ducts, are positioned independently along therespective four sides of each heat conduction plate.

The substantially L shape in the present invention indicates a curvedstate in which the inlets and outlets of the first and second air ductsare not positioned in the same plane.

The air-tightness in the present invention can be ensured by providingair duct end faces along the inlets and outlets of the air ducts, andbringing the air duct end faces of a first heat conduction plate intocontact with the side surfaces of the outer peripheral ribs on a secondheat conduction plate adjacent to the first heat conduction plate, andthe air duct end faces on the second heat conduction plate into contactwith the side surfaces of the outer peripheral ribs on the first heatconduction plate adjacent to the second heat conduction plate

INDUSTRIAL APPLICABILITY

The present invention provides a heat exchanger having improved basicperformance, e.g. improving heat exchange efficiency and reducingpressure loss, as well as improved productivity and strength.

The present invention can be used for heat exchange ventilators or airconditioners using heat exchangers.

1. A heat exchanger comprising: a first heat conduction plate and asecond heat conduction plate both in substantially a square shape, eachof the first and second heat conduction plates including: a plurality ofsubstantially L-shaped air duct ribs forming a plurality ofsubstantially L-shaped air ducts and heat conduction planes; an outerperipheral rib for shielding leak of fluid flowing through the air ductsto an outside of the heat conduction plate; and air-tightness ensuringmeans; wherein the first heat conduction plate and the second heatconduction plate are integrally molded of one sheet material, and arealternately laminated on top of each other.
 2. The heat exchanger ofclaim 1, wherein the air-tightness ensuring means includes an air ductend face along each of inlets and outlets of the plurality of air ducts,and the air duct end face of the first heat conduction plate is incontact with a side surface of the outer peripheral rib on the secondheat conduction plate adjacent to the first heat conduction plate, andthe air duct end face of the second heat conduction plate is in contactwith a side surface of the outer peripheral rib on the first heatconduction plate adjacent to the second heat conduction plate.
 3. A heatexchanger comprising: a first heat conduction plate and a second heatconduction plate both in substantially a square shape, the first heatconduction plate including: a plurality of substantially L-shaped airduct ribs formed into hollow protrusions substantially parallel to eachother at substantially an equal spacing, the plurality of air duct ribsforming a plurality of substantially L-shaped air ducts and heatconduction planes; air duct end faces provided along an inlet and outletof the air ducts so as to orthogonal to the inlet and outlet, formed bybending the heat conduction planes in a direction opposite to aprotruding direction of the air duct ribs; a plurality of first hollowprotrusions provided at both ends of each of the air duct ribs in theprotruding direction of the air duct ribs, each protrusion having a sidesurface substantially parallel to the air duct end faces, and a heightlarger than that of the plurality of air duct ribs in the protrudingdirection thereof; a first outer periphery (a) sandwiched between theinlet and outlet of the air ducts, and a first outer periphery (b)diagonal thereto both provided along outer peripheries of the first heatconduction plate other than the inlet and outlet of the air ducts, thefirst outer peripheries (a, b) being substantially parallel tosubstantially central portions of the plurality of L-shaped air ductribs; and a pair of second outer peripheries (a, b) provided along outerperipheries adjacent to the inlet and outlet of the air ducts on anopposite side of first outer periphery (a), the second outer periphery(a) being substantially parallel to first outer peripheries (a, b), thesecond outer periphery (b) being substantially orthogonal to first outerperipheries (a, b), wherein, each of the first outer peripheries (a, b)includes a first outer peripheral rib formed by the heat conductionplanes into a hollow protrusion in the protruding direction of the airduct ribs and having a height larger than that of the air duct ribs inthe protruding direction thereof, an outer side surface of the firstouter peripheral rib is bent in a direction opposite to the protrudingdirection of the air duct ribs so as to have a height larger than thatof the first outer peripheral rib from the heat conduction planes in theprotruding direction thereof; and each of the second outer peripheries(a, b) includes a second outer peripheral rib formed by the heatconduction planes into a hollow protrusion in the protruding directionof the air duct ribs and having a height equal to that of the air ductribs in the protruding direction thereof, and a central portion of anouter side surface of each of the second outer peripheral ribs is bentto a same surface of the heat conduction planes so as to have a slottherein; and each of air duct end face covers bent to a same position towhich the air duct end faces are bent is provided at each end of theouter side surfaces of the second outer peripheral ribs, a secondprotrusion formed into a hollow protrusion in the protruding directionof the air duct ribs is provided at an air duct end face side of eachsecond outer peripheral rib, and the second protrusion has a heightequal to the height of the first protrusions in a protruding directionthereof; and the second heat conduction plate analogous to the firstheat conduction plate wherein, in the second heat conduction plate, aheight of a first outer peripheral rib is equal to the height of the airduct ribs in the protruding direction thereof, and a width of the firstouter peripheral rib is larger than a width of the first outerperipheral ribs on the first heat conduction plate; wherein, the firstheat conduction plate and the second heat conduction plate areintegrally molded of one sheet material, and are alternately laminatedso that the first outer peripheral ribs on the second heat conductionplate overlaps the first outer peripheral ribs on the first heatconduction plate; laminating the first heat conduction plate and thesecond heat conduction plate forms first air ducts and second air ductsalternately; when the first heat conduction plate and the second heatconduction plate are alternately laminated, top surfaces of the air ductribs, first protrusions, first outer peripheral ribs, second outerperipheral ribs, and second protrusions on one of the first and secondheat conduction plates are in contact with an other one of the first andsecond heat conduction plates laminated thereon, the side surfaces ofthe first protrusions on one of the first and second heat conductionplates parallel to the air duct end faces are in contact with inner sidesurfaces of the corresponding second outer peripheral ribs provided onan other one of the first and second heat conduction plates positionedon the one of the first and second heat conduction plates, the air ductend faces of one of the heat conduction plates are in contact with theouter side surfaces of the corresponding second outer peripheral ribs onan other one of the heat conduction plates positioned under the one ofthe heat conduction plates, side surfaces of the first outer peripheralribs provided on the first and second heat conduction plates are incontact with each other, and the air duct end face covers on one of thefirst and second heat conduction plates are in contact with thecorresponding first outer peripheral ribs and the second protrusionsprovided at end faces of the corresponding second outer peripheral ribson an other of the first and second heat conduction plates positionedunder the one of the first and second heat conduction plates.
 4. Theheat exchanger of claim 3, wherein the air duct ribs on the first heatconduction plate and second heat conduction plate are in verticallyaligned positions, in substantially central portions of the air ductribs substantially parallel to the first outer peripheral ribs.
 5. Theheat exchanger of claim 4, further comprising: a plurality of thirdprotrusions formed into hollow protrusions in the protruding directionof the air duct ribs, on substantially the central portions of the airduct ribs substantially parallel to the first outer peripheral ribs onthe first heat conduction plate and the second heat conduction platewherein each of the third protrusions has a height equal to that of thefirst protrusions in the protruding direction thereof; and top surfacesof the third protrusions on one of the first and second heat conductionplates are in contact with bottom surfaces of the air duct ribs on another one of the first and second heat conduction plates positioned onthe one of the first and second heat conduction plates.
 6. The heatexchanger of claim 4, wherein, in substantially the central portions ofthe air duct ribs substantially parallel to the first outer peripheralribs, a width of the air duct ribs on at least one of the first heatconduction plate and the second heat conduction plate is intermittentlyenlarged.
 7. The heat exchanger of claim 4, wherein the plurality ofthird protrusions are provided on substantially the central portions ofthe air duct ribs substantially parallel to the first outer peripheralribs on at least one of the first heat conduction plate and the secondheat conduction plate; and a width of the air duct ribs on an other oneof the first heat conduction plate and the second heat conduction plateis intermittently enlarged.
 8. The heat exchanger of claim 4, whereinthe height of the air duct ribs on one of the first heat exchange plateand the second heat conduction plate is equal to the height of the firstprotrusions in the protruding direction thereof; and a width of the airduct ribs on an other one of the first heat conduction plate and thesecond heat conduction plate is larger than the width of the air ductribs on the one of the first and second heat conduction plates.
 9. Theheat exchanger of claim 3, wherein the second protrusions on one of thefirst heat conduction plate and the second heat conduction plate aresubstantially orthogonal to the second protrusions on an other one ofthe first and second heat conduction plates positioned on the one of thefirst and second heat conduction plates; and the top surfaces of thesecond protrusions provided on one of the first and second heat exchangepalate are in contact with bottom surfaces of the second outerperipheral ribs on an other one of the first and second heat conductionplates positioned on the one of the first and second heat conductionplates.
 10. The heat exchanger of claim 3, further comprising: side facereinforcing projections provided on the top surfaces of the first outerperipheral ribs on the second heat conduction plate, wherein, when thefirst heat conduction plate and the second heat conduction plate arealternately laminated, the top surfaces of the first outer peripheralribs on the first heat conduction plate are in contact with the bottomsurfaces of the first outer peripheral ribs on the second heatconduction plate; the top surfaces of the first outer peripheral ribs onthe second heat conduction plate are in contact with bottom surfaces ofthe heat conduction planes on the first heat conduction plate; and topand side surfaces of the side face reinforcing projections on the firstouter peripheral ribs on the second heat conduction plate are in contactwith the bottom and side surfaces of the first outer peripheral ribs onthe first heat conduction plate, respectively.
 11. The heat exchanger ofclaim 10, wherein the side face reinforcing protrusions areintermittently formed.
 12. The heat exchanger of claim 11, wherein theside face reinforcing projections are provided on the top surfaces ofthe first outer peripheral ribs on the first heat conduction plate andthe second heat conduction plate; when the first heat conduction plateand the second heat conduction plate are alternately laminated, top andside surfaces of the side face reinforcing projections on the first heatconduction plate are in contact with the bottom and side surfaces of thefirst outer peripheral ribs on the second heat conduction plate,respectively; and the top and side surfaces of the side face reinforcingprojections on the second heat conduction plate are in contact with thebottom and side surfaces of the first outer peripheral ribs on the firstheat conduction plate, respectively.
 13. The heat exchanger of claim 11,wherein when the first heat conduction plate and second heat conductionplate are alternately laminated, the top and side surfaces of the firstouter peripheral ribs on the first heat conduction plate are in contactwith the bottom and side surfaces of the first outer peripheral ribs onthe second heat conduction plates, respectively; and the top and sidesurfaces of the side face reinforcing projections formed on the firstouter peripheral ribs on the second heat conduction plate are in contactwith the bottom and side surfaces of the first outer peripheral ribs onthe first heat conduction plate, respectively.
 14. The heat exchanger ofclaim 1, wherein the sheet material contains rubber particles dispersedin a resin.
 15. The heat exchanger of claim 14, wherein the resin is astyrene-based resin.
 16. The heat exchanger of claim 14, wherein theresin is high impact polystyrene.
 17. The heat exchanger of claim 14,wherein the resin is an ABS resin.